A recent introduction in communications technology has been the introduction of network protocols for the delivery of multimedia services to terminals. Typical of these protocols is the so-called Internet (IP) protocol in which information is carried in packets. In these protocols, the services are delivered to terminals over a local area network. The services are generally provided by other networks, e.g. N-ISDN or B-ISDN networks and, as the service providing networks will often be remote from the local area network delivering the services, there is a need for an information transport mechanism to carry traffic between the networks. This problem has been addressed by the development of the Digital Audio-Visual Council (DAVIC) specification 1.1, December 1996, which proposes the use of an asynchronous transfer mode (ATM) network as a transport medium.
A general discussion of multimedia communications in local area networks is given by G A Thom in IEEE Communications Magazine, December 1996, pp 52 to 56. An ATM-UNI-LAN communication method and apparatus is described in specification U.S. Pat. No. 5,528,590.
There is an increasing need to interface local area networks of this type with broad band ATM (asynchronous transfer mode) virtual circuit switched networks to take full advantage of the information traffic handling capabilities of those networks so that services provided by remote networks can be readily accessed.
In such an arrangement, interfaces must be provided both between the local area network and the broadband ATM network and between the ATM network and the service provider network to take account of the different transmission protocols and signalling protocols for the two types of network. The service provider must also take account of the switched virtual circuit nature of the broadband network. These interfaces, which are generally referred to as gateways provide translation between the virtual circuit switched protocol of the ATM network and the packet and circuit switched protocols of the networks interfacing therewith. At present this requires the provision of a number of different gateways with a consequent penalty in terms of cost and complexity.